High-Q terahertz microcavities in silicon photonic crystal slabs

Photonic crystal cavities consisting of three holes missing along a principal axis in a triangular lattice of holes in a silicon slab were fabricated. Each cavity was built into a waveguide to form a Lorentzian filter. Two samples were constructed with lattice constants a=80 and 76 μm, with a radius r=0.30a in a 44 μm thick high-resistivity silicon wafer. Transmission experiment show a single sharp resonance near 1 THz in each sample with quality factor Q as high as 1020. Contributions to the measured Q from cavity-waveguide coupling, radiative loss, and material loss are determined.